Adding upstream version 18.2.2.upstream/18.2.2

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 738 insertions, 0 deletions

diff --git a/src/rocksdb/test_util/testutil.cc b/src/rocksdb/test_util/testutil.cc
new file mode 100644
index 000000000..5e1b909f9
--- /dev/null
+++ b/src/rocksdb/test_util/testutil.cc
@@ -0,0 +1,738 @@
+//  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+//
+// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file. See the AUTHORS file for names of contributors.
+
+#include "test_util/testutil.h"
+
+#include <fcntl.h>
+#include <sys/stat.h>
+
+#include <array>
+#include <cctype>
+#include <fstream>
+#include <sstream>
+
+#include "db/memtable_list.h"
+#include "env/composite_env_wrapper.h"
+#include "file/random_access_file_reader.h"
+#include "file/sequence_file_reader.h"
+#include "file/writable_file_writer.h"
+#include "port/port.h"
+#include "rocksdb/convenience.h"
+#include "rocksdb/system_clock.h"
+#include "rocksdb/utilities/object_registry.h"
+#include "test_util/mock_time_env.h"
+#include "test_util/sync_point.h"
+#include "util/random.h"
+
+#ifndef ROCKSDB_UNITTESTS_WITH_CUSTOM_OBJECTS_FROM_STATIC_LIBS
+void RegisterCustomObjects(int /*argc*/, char** /*argv*/) {}
+#endif
+
+namespace ROCKSDB_NAMESPACE {
+namespace test {
+
+const uint32_t kDefaultFormatVersion = BlockBasedTableOptions().format_version;
+const std::set<uint32_t> kFooterFormatVersionsToTest{
+    5U,
+    // In case any interesting future changes
+    kDefaultFormatVersion,
+    kLatestFormatVersion,
+};
+
+std::string RandomKey(Random* rnd, int len, RandomKeyType type) {
+  // Make sure to generate a wide variety of characters so we
+  // test the boundary conditions for short-key optimizations.
+  static const char kTestChars[] = {'\0', '\1', 'a',    'b',    'c',
+                                    'd',  'e',  '\xfd', '\xfe', '\xff'};
+  std::string result;
+  for (int i = 0; i < len; i++) {
+    std::size_t indx = 0;
+    switch (type) {
+      case RandomKeyType::RANDOM:
+        indx = rnd->Uniform(sizeof(kTestChars));
+        break;
+      case RandomKeyType::LARGEST:
+        indx = sizeof(kTestChars) - 1;
+        break;
+      case RandomKeyType::MIDDLE:
+        indx = sizeof(kTestChars) / 2;
+        break;
+      case RandomKeyType::SMALLEST:
+        indx = 0;
+        break;
+    }
+    result += kTestChars[indx];
+  }
+  return result;
+}
+
+extern Slice CompressibleString(Random* rnd, double compressed_fraction,
+                                int len, std::string* dst) {
+  int raw = static_cast<int>(len * compressed_fraction);
+  if (raw < 1) raw = 1;
+  std::string raw_data = rnd->RandomString(raw);
+
+  // Duplicate the random data until we have filled "len" bytes
+  dst->clear();
+  while (dst->size() < (unsigned int)len) {
+    dst->append(raw_data);
+  }
+  dst->resize(len);
+  return Slice(*dst);
+}
+
+namespace {
+class Uint64ComparatorImpl : public Comparator {
+ public:
+  Uint64ComparatorImpl() {}
+
+  const char* Name() const override { return "rocksdb.Uint64Comparator"; }
+
+  int Compare(const Slice& a, const Slice& b) const override {
+    assert(a.size() == sizeof(uint64_t) && b.size() == sizeof(uint64_t));
+    const uint64_t* left = reinterpret_cast<const uint64_t*>(a.data());
+    const uint64_t* right = reinterpret_cast<const uint64_t*>(b.data());
+    uint64_t leftValue;
+    uint64_t rightValue;
+    GetUnaligned(left, &leftValue);
+    GetUnaligned(right, &rightValue);
+    if (leftValue == rightValue) {
+      return 0;
+    } else if (leftValue < rightValue) {
+      return -1;
+    } else {
+      return 1;
+    }
+  }
+
+  void FindShortestSeparator(std::string* /*start*/,
+                             const Slice& /*limit*/) const override {
+    return;
+  }
+
+  void FindShortSuccessor(std::string* /*key*/) const override { return; }
+};
+}  // namespace
+
+const Comparator* Uint64Comparator() {
+  static Uint64ComparatorImpl uint64comp;
+  return &uint64comp;
+}
+
+const Comparator* BytewiseComparatorWithU64TsWrapper() {
+  ConfigOptions config_options;
+  const Comparator* user_comparator = nullptr;
+  Status s = Comparator::CreateFromString(
+      config_options, "leveldb.BytewiseComparator.u64ts", &user_comparator);
+  s.PermitUncheckedError();
+  return user_comparator;
+}
+
+void CorruptKeyType(InternalKey* ikey) {
+  std::string keystr = ikey->Encode().ToString();
+  keystr[keystr.size() - 8] = kTypeLogData;
+  ikey->DecodeFrom(Slice(keystr.data(), keystr.size()));
+}
+
+std::string KeyStr(const std::string& user_key, const SequenceNumber& seq,
+                   const ValueType& t, bool corrupt) {
+  InternalKey k(user_key, seq, t);
+  if (corrupt) {
+    CorruptKeyType(&k);
+  }
+  return k.Encode().ToString();
+}
+
+std::string KeyStr(uint64_t ts, const std::string& user_key,
+                   const SequenceNumber& seq, const ValueType& t,
+                   bool corrupt) {
+  std::string user_key_with_ts(user_key);
+  std::string ts_str;
+  PutFixed64(&ts_str, ts);
+  user_key_with_ts.append(ts_str);
+  return KeyStr(user_key_with_ts, seq, t, corrupt);
+}
+
+bool SleepingBackgroundTask::TimedWaitUntilSleeping(uint64_t wait_time) {
+  auto abs_time = SystemClock::Default()->NowMicros() + wait_time;
+  MutexLock l(&mutex_);
+  while (!sleeping_ || !should_sleep_) {
+    if (bg_cv_.TimedWait(abs_time)) {
+      return true;
+    }
+  }
+  return false;
+}
+
+bool SleepingBackgroundTask::TimedWaitUntilDone(uint64_t wait_time) {
+  auto abs_time = SystemClock::Default()->NowMicros() + wait_time;
+  MutexLock l(&mutex_);
+  while (!done_with_sleep_) {
+    if (bg_cv_.TimedWait(abs_time)) {
+      return true;
+    }
+  }
+  return false;
+}
+
+std::string RandomName(Random* rnd, const size_t len) {
+  std::stringstream ss;
+  for (size_t i = 0; i < len; ++i) {
+    ss << static_cast<char>(rnd->Uniform(26) + 'a');
+  }
+  return ss.str();
+}
+
+CompressionType RandomCompressionType(Random* rnd) {
+  auto ret = static_cast<CompressionType>(rnd->Uniform(6));
+  while (!CompressionTypeSupported(ret)) {
+    ret = static_cast<CompressionType>((static_cast<int>(ret) + 1) % 6);
+  }
+  return ret;
+}
+
+void RandomCompressionTypeVector(const size_t count,
+                                 std::vector<CompressionType>* types,
+                                 Random* rnd) {
+  types->clear();
+  for (size_t i = 0; i < count; ++i) {
+    types->emplace_back(RandomCompressionType(rnd));
+  }
+}
+
+const SliceTransform* RandomSliceTransform(Random* rnd, int pre_defined) {
+  int random_num = pre_defined >= 0 ? pre_defined : rnd->Uniform(4);
+  switch (random_num) {
+    case 0:
+      return NewFixedPrefixTransform(rnd->Uniform(20) + 1);
+    case 1:
+      return NewCappedPrefixTransform(rnd->Uniform(20) + 1);
+    case 2:
+      return NewNoopTransform();
+    default:
+      return nullptr;
+  }
+}
+
+BlockBasedTableOptions RandomBlockBasedTableOptions(Random* rnd) {
+  BlockBasedTableOptions opt;
+  opt.cache_index_and_filter_blocks = rnd->Uniform(2);
+  opt.pin_l0_filter_and_index_blocks_in_cache = rnd->Uniform(2);
+  opt.pin_top_level_index_and_filter = rnd->Uniform(2);
+  using IndexType = BlockBasedTableOptions::IndexType;
+  const std::array<IndexType, 4> index_types = {
+      {IndexType::kBinarySearch, IndexType::kHashSearch,
+       IndexType::kTwoLevelIndexSearch, IndexType::kBinarySearchWithFirstKey}};
+  opt.index_type =
+      index_types[rnd->Uniform(static_cast<int>(index_types.size()))];
+  opt.checksum = static_cast<ChecksumType>(rnd->Uniform(3));
+  opt.block_size = rnd->Uniform(10000000);
+  opt.block_size_deviation = rnd->Uniform(100);
+  opt.block_restart_interval = rnd->Uniform(100);
+  opt.index_block_restart_interval = rnd->Uniform(100);
+  opt.whole_key_filtering = rnd->Uniform(2);
+
+  return opt;
+}
+
+TableFactory* RandomTableFactory(Random* rnd, int pre_defined) {
+#ifndef ROCKSDB_LITE
+  int random_num = pre_defined >= 0 ? pre_defined : rnd->Uniform(4);
+  switch (random_num) {
+    case 0:
+      return NewPlainTableFactory();
+    case 1:
+      return NewCuckooTableFactory();
+    default:
+      return NewBlockBasedTableFactory();
+  }
+#else
+  (void)rnd;
+  (void)pre_defined;
+  return NewBlockBasedTableFactory();
+#endif  // !ROCKSDB_LITE
+}
+
+MergeOperator* RandomMergeOperator(Random* rnd) {
+  return new ChanglingMergeOperator(RandomName(rnd, 10));
+}
+
+CompactionFilter* RandomCompactionFilter(Random* rnd) {
+  return new ChanglingCompactionFilter(RandomName(rnd, 10));
+}
+
+CompactionFilterFactory* RandomCompactionFilterFactory(Random* rnd) {
+  return new ChanglingCompactionFilterFactory(RandomName(rnd, 10));
+}
+
+void RandomInitDBOptions(DBOptions* db_opt, Random* rnd) {
+  // boolean options
+  db_opt->advise_random_on_open = rnd->Uniform(2);
+  db_opt->allow_mmap_reads = rnd->Uniform(2);
+  db_opt->allow_mmap_writes = rnd->Uniform(2);
+  db_opt->use_direct_reads = rnd->Uniform(2);
+  db_opt->use_direct_io_for_flush_and_compaction = rnd->Uniform(2);
+  db_opt->create_if_missing = rnd->Uniform(2);
+  db_opt->create_missing_column_families = rnd->Uniform(2);
+  db_opt->enable_thread_tracking = rnd->Uniform(2);
+  db_opt->error_if_exists = rnd->Uniform(2);
+  db_opt->is_fd_close_on_exec = rnd->Uniform(2);
+  db_opt->paranoid_checks = rnd->Uniform(2);
+  db_opt->track_and_verify_wals_in_manifest = rnd->Uniform(2);
+  db_opt->verify_sst_unique_id_in_manifest = rnd->Uniform(2);
+  db_opt->skip_stats_update_on_db_open = rnd->Uniform(2);
+  db_opt->skip_checking_sst_file_sizes_on_db_open = rnd->Uniform(2);
+  db_opt->use_adaptive_mutex = rnd->Uniform(2);
+  db_opt->use_fsync = rnd->Uniform(2);
+  db_opt->recycle_log_file_num = rnd->Uniform(2);
+  db_opt->avoid_flush_during_recovery = rnd->Uniform(2);
+  db_opt->avoid_flush_during_shutdown = rnd->Uniform(2);
+  db_opt->enforce_single_del_contracts = rnd->Uniform(2);
+
+  // int options
+  db_opt->max_background_compactions = rnd->Uniform(100);
+  db_opt->max_background_flushes = rnd->Uniform(100);
+  db_opt->max_file_opening_threads = rnd->Uniform(100);
+  db_opt->max_open_files = rnd->Uniform(100);
+  db_opt->table_cache_numshardbits = rnd->Uniform(100);
+
+  // size_t options
+  db_opt->db_write_buffer_size = rnd->Uniform(10000);
+  db_opt->keep_log_file_num = rnd->Uniform(10000);
+  db_opt->log_file_time_to_roll = rnd->Uniform(10000);
+  db_opt->manifest_preallocation_size = rnd->Uniform(10000);
+  db_opt->max_log_file_size = rnd->Uniform(10000);
+
+  // std::string options
+  db_opt->db_log_dir = "path/to/db_log_dir";
+  db_opt->wal_dir = "path/to/wal_dir";
+
+  // uint32_t options
+  db_opt->max_subcompactions = rnd->Uniform(100000);
+
+  // uint64_t options
+  static const uint64_t uint_max = static_cast<uint64_t>(UINT_MAX);
+  db_opt->WAL_size_limit_MB = uint_max + rnd->Uniform(100000);
+  db_opt->WAL_ttl_seconds = uint_max + rnd->Uniform(100000);
+  db_opt->bytes_per_sync = uint_max + rnd->Uniform(100000);
+  db_opt->delayed_write_rate = uint_max + rnd->Uniform(100000);
+  db_opt->delete_obsolete_files_period_micros = uint_max + rnd->Uniform(100000);
+  db_opt->max_manifest_file_size = uint_max + rnd->Uniform(100000);
+  db_opt->max_total_wal_size = uint_max + rnd->Uniform(100000);
+  db_opt->wal_bytes_per_sync = uint_max + rnd->Uniform(100000);
+
+  // unsigned int options
+  db_opt->stats_dump_period_sec = rnd->Uniform(100000);
+}
+
+void RandomInitCFOptions(ColumnFamilyOptions* cf_opt, DBOptions& db_options,
+                         Random* rnd) {
+  cf_opt->compaction_style = (CompactionStyle)(rnd->Uniform(4));
+
+  // boolean options
+  cf_opt->report_bg_io_stats = rnd->Uniform(2);
+  cf_opt->disable_auto_compactions = rnd->Uniform(2);
+  cf_opt->inplace_update_support = rnd->Uniform(2);
+  cf_opt->level_compaction_dynamic_level_bytes = rnd->Uniform(2);
+  cf_opt->optimize_filters_for_hits = rnd->Uniform(2);
+  cf_opt->paranoid_file_checks = rnd->Uniform(2);
+  cf_opt->force_consistency_checks = rnd->Uniform(2);
+  cf_opt->compaction_options_fifo.allow_compaction = rnd->Uniform(2);
+  cf_opt->memtable_whole_key_filtering = rnd->Uniform(2);
+  cf_opt->enable_blob_files = rnd->Uniform(2);
+  cf_opt->enable_blob_garbage_collection = rnd->Uniform(2);
+
+  // double options
+  cf_opt->memtable_prefix_bloom_size_ratio =
+      static_cast<double>(rnd->Uniform(10000)) / 20000.0;
+  cf_opt->blob_garbage_collection_age_cutoff = rnd->Uniform(10000) / 10000.0;
+  cf_opt->blob_garbage_collection_force_threshold =
+      rnd->Uniform(10000) / 10000.0;
+
+  // int options
+  cf_opt->level0_file_num_compaction_trigger = rnd->Uniform(100);
+  cf_opt->level0_slowdown_writes_trigger = rnd->Uniform(100);
+  cf_opt->level0_stop_writes_trigger = rnd->Uniform(100);
+  cf_opt->max_bytes_for_level_multiplier = rnd->Uniform(100);
+  cf_opt->max_write_buffer_number = rnd->Uniform(100);
+  cf_opt->max_write_buffer_number_to_maintain = rnd->Uniform(100);
+  cf_opt->max_write_buffer_size_to_maintain = rnd->Uniform(10000);
+  cf_opt->min_write_buffer_number_to_merge = rnd->Uniform(100);
+  cf_opt->num_levels = rnd->Uniform(100);
+  cf_opt->target_file_size_multiplier = rnd->Uniform(100);
+
+  // vector int options
+  cf_opt->max_bytes_for_level_multiplier_additional.resize(cf_opt->num_levels);
+  for (int i = 0; i < cf_opt->num_levels; i++) {
+    cf_opt->max_bytes_for_level_multiplier_additional[i] = rnd->Uniform(100);
+  }
+
+  // size_t options
+  cf_opt->arena_block_size = rnd->Uniform(10000);
+  cf_opt->inplace_update_num_locks = rnd->Uniform(10000);
+  cf_opt->max_successive_merges = rnd->Uniform(10000);
+  cf_opt->memtable_huge_page_size = rnd->Uniform(10000);
+  cf_opt->write_buffer_size = rnd->Uniform(10000);
+
+  // uint32_t options
+  cf_opt->bloom_locality = rnd->Uniform(10000);
+  cf_opt->max_bytes_for_level_base = rnd->Uniform(10000);
+
+  // uint64_t options
+  static const uint64_t uint_max = static_cast<uint64_t>(UINT_MAX);
+  cf_opt->ttl =
+      db_options.max_open_files == -1 ? uint_max + rnd->Uniform(10000) : 0;
+  cf_opt->periodic_compaction_seconds =
+      db_options.max_open_files == -1 ? uint_max + rnd->Uniform(10000) : 0;
+  cf_opt->max_sequential_skip_in_iterations = uint_max + rnd->Uniform(10000);
+  cf_opt->target_file_size_base = uint_max + rnd->Uniform(10000);
+  cf_opt->max_compaction_bytes =
+      cf_opt->target_file_size_base * rnd->Uniform(100);
+  cf_opt->compaction_options_fifo.max_table_files_size =
+      uint_max + rnd->Uniform(10000);
+  cf_opt->min_blob_size = uint_max + rnd->Uniform(10000);
+  cf_opt->blob_file_size = uint_max + rnd->Uniform(10000);
+  cf_opt->blob_compaction_readahead_size = uint_max + rnd->Uniform(10000);
+
+  // pointer typed options
+  cf_opt->prefix_extractor.reset(RandomSliceTransform(rnd));
+  cf_opt->table_factory.reset(RandomTableFactory(rnd));
+  cf_opt->merge_operator.reset(RandomMergeOperator(rnd));
+  if (cf_opt->compaction_filter) {
+    delete cf_opt->compaction_filter;
+  }
+  cf_opt->compaction_filter = RandomCompactionFilter(rnd);
+  cf_opt->compaction_filter_factory.reset(RandomCompactionFilterFactory(rnd));
+
+  // custom typed options
+  cf_opt->compression = RandomCompressionType(rnd);
+  RandomCompressionTypeVector(cf_opt->num_levels,
+                              &cf_opt->compression_per_level, rnd);
+  cf_opt->blob_compression_type = RandomCompressionType(rnd);
+}
+
+bool IsDirectIOSupported(Env* env, const std::string& dir) {
+  EnvOptions env_options;
+  env_options.use_mmap_writes = false;
+  env_options.use_direct_writes = true;
+  std::string tmp = TempFileName(dir, 999);
+  Status s;
+  {
+    std::unique_ptr<WritableFile> file;
+    s = env->NewWritableFile(tmp, &file, env_options);
+  }
+  if (s.ok()) {
+    s = env->DeleteFile(tmp);
+  }
+  return s.ok();
+}
+
+bool IsPrefetchSupported(const std::shared_ptr<FileSystem>& fs,
+                         const std::string& dir) {
+  bool supported = false;
+  std::string tmp = TempFileName(dir, 999);
+  Random rnd(301);
+  std::string test_string = rnd.RandomString(4096);
+  Slice data(test_string);
+  Status s = WriteStringToFile(fs.get(), data, tmp, true);
+  if (s.ok()) {
+    std::unique_ptr<FSRandomAccessFile> file;
+    auto io_s = fs->NewRandomAccessFile(tmp, FileOptions(), &file, nullptr);
+    if (io_s.ok()) {
+      supported = !(file->Prefetch(0, data.size(), IOOptions(), nullptr)
+                        .IsNotSupported());
+    }
+    s = fs->DeleteFile(tmp, IOOptions(), nullptr);
+  }
+  return s.ok() && supported;
+}
+
+size_t GetLinesCount(const std::string& fname, const std::string& pattern) {
+  std::stringstream ssbuf;
+  std::string line;
+  size_t count = 0;
+
+  std::ifstream inFile(fname.c_str());
+  ssbuf << inFile.rdbuf();
+
+  while (getline(ssbuf, line)) {
+    if (line.find(pattern) != std::string::npos) {
+      count++;
+    }
+  }
+
+  return count;
+}
+
+Status CorruptFile(Env* env, const std::string& fname, int offset,
+                   int bytes_to_corrupt, bool verify_checksum /*=true*/) {
+  uint64_t size;
+  Status s = env->GetFileSize(fname, &size);
+  if (!s.ok()) {
+    return s;
+  } else if (offset < 0) {
+    // Relative to end of file; make it absolute
+    if (-offset > static_cast<int>(size)) {
+      offset = 0;
+    } else {
+      offset = static_cast<int>(size + offset);
+    }
+  }
+  if (offset > static_cast<int>(size)) {
+    offset = static_cast<int>(size);
+  }
+  if (offset + bytes_to_corrupt > static_cast<int>(size)) {
+    bytes_to_corrupt = static_cast<int>(size - offset);
+  }
+
+  // Do it
+  std::string contents;
+  s = ReadFileToString(env, fname, &contents);
+  if (s.ok()) {
+    for (int i = 0; i < bytes_to_corrupt; i++) {
+      contents[i + offset] ^= 0x80;
+    }
+    s = WriteStringToFile(env, contents, fname);
+  }
+  if (s.ok() && verify_checksum) {
+#ifndef ROCKSDB_LITE
+    Options options;
+    options.env = env;
+    EnvOptions env_options;
+    Status v = VerifySstFileChecksum(options, env_options, fname);
+    assert(!v.ok());
+#endif
+  }
+  return s;
+}
+
+Status TruncateFile(Env* env, const std::string& fname, uint64_t new_length) {
+  uint64_t old_length;
+  Status s = env->GetFileSize(fname, &old_length);
+  if (!s.ok() || new_length == old_length) {
+    return s;
+  }
+  // Do it
+  std::string contents;
+  s = ReadFileToString(env, fname, &contents);
+  if (s.ok()) {
+    contents.resize(static_cast<size_t>(new_length), 'b');
+    s = WriteStringToFile(env, contents, fname);
+  }
+  return s;
+}
+
+// Try and delete a directory if it exists
+Status TryDeleteDir(Env* env, const std::string& dirname) {
+  bool is_dir = false;
+  Status s = env->IsDirectory(dirname, &is_dir);
+  if (s.ok() && is_dir) {
+    s = env->DeleteDir(dirname);
+  }
+  return s;
+}
+
+// Delete a directory if it exists
+void DeleteDir(Env* env, const std::string& dirname) {
+  TryDeleteDir(env, dirname).PermitUncheckedError();
+}
+
+Status CreateEnvFromSystem(const ConfigOptions& config_options, Env** result,
+                           std::shared_ptr<Env>* guard) {
+  const char* env_uri = getenv("TEST_ENV_URI");
+  const char* fs_uri = getenv("TEST_FS_URI");
+  if (env_uri || fs_uri) {
+    return Env::CreateFromUri(config_options,
+                              (env_uri != nullptr) ? env_uri : "",
+                              (fs_uri != nullptr) ? fs_uri : "", result, guard);
+  } else {
+    // Neither specified.  Use the default
+    *result = config_options.env;
+    guard->reset();
+    return Status::OK();
+  }
+}
+namespace {
+// A hacky skip list mem table that triggers flush after number of entries.
+class SpecialMemTableRep : public MemTableRep {
+ public:
+  explicit SpecialMemTableRep(Allocator* allocator, MemTableRep* memtable,
+                              int num_entries_flush)
+      : MemTableRep(allocator),
+        memtable_(memtable),
+        num_entries_flush_(num_entries_flush),
+        num_entries_(0) {}
+
+  virtual KeyHandle Allocate(const size_t len, char** buf) override {
+    return memtable_->Allocate(len, buf);
+  }
+
+  // Insert key into the list.
+  // REQUIRES: nothing that compares equal to key is currently in the list.
+  virtual void Insert(KeyHandle handle) override {
+    num_entries_++;
+    memtable_->Insert(handle);
+  }
+
+  void InsertConcurrently(KeyHandle handle) override {
+    num_entries_++;
+    memtable_->Insert(handle);
+  }
+
+  // Returns true iff an entry that compares equal to key is in the list.
+  virtual bool Contains(const char* key) const override {
+    return memtable_->Contains(key);
+  }
+
+  virtual size_t ApproximateMemoryUsage() override {
+    // Return a high memory usage when number of entries exceeds the threshold
+    // to trigger a flush.
+    return (num_entries_ < num_entries_flush_) ? 0 : 1024 * 1024 * 1024;
+  }
+
+  virtual void Get(const LookupKey& k, void* callback_args,
+                   bool (*callback_func)(void* arg,
+                                         const char* entry)) override {
+    memtable_->Get(k, callback_args, callback_func);
+  }
+
+  uint64_t ApproximateNumEntries(const Slice& start_ikey,
+                                 const Slice& end_ikey) override {
+    return memtable_->ApproximateNumEntries(start_ikey, end_ikey);
+  }
+
+  virtual MemTableRep::Iterator* GetIterator(Arena* arena = nullptr) override {
+    return memtable_->GetIterator(arena);
+  }
+
+  virtual ~SpecialMemTableRep() override {}
+
+ private:
+  std::unique_ptr<MemTableRep> memtable_;
+  int num_entries_flush_;
+  int num_entries_;
+};
+class SpecialSkipListFactory : public MemTableRepFactory {
+ public:
+#ifndef ROCKSDB_LITE
+  static bool Register(ObjectLibrary& library, const std::string& /*arg*/) {
+    library.AddFactory<MemTableRepFactory>(
+        ObjectLibrary::PatternEntry(SpecialSkipListFactory::kClassName(), true)
+            .AddNumber(":"),
+        [](const std::string& uri, std::unique_ptr<MemTableRepFactory>* guard,
+           std::string* /* errmsg */) {
+          auto colon = uri.find(":");
+          if (colon != std::string::npos) {
+            auto count = ParseInt(uri.substr(colon + 1));
+            guard->reset(new SpecialSkipListFactory(count));
+          } else {
+            guard->reset(new SpecialSkipListFactory(2));
+          }
+          return guard->get();
+        });
+    return true;
+  }
+#endif  // ROCKSDB_LITE
+  // After number of inserts exceeds `num_entries_flush` in a mem table, trigger
+  // flush.
+  explicit SpecialSkipListFactory(int num_entries_flush)
+      : num_entries_flush_(num_entries_flush) {}
+
+  using MemTableRepFactory::CreateMemTableRep;
+  virtual MemTableRep* CreateMemTableRep(
+      const MemTableRep::KeyComparator& compare, Allocator* allocator,
+      const SliceTransform* transform, Logger* /*logger*/) override {
+    return new SpecialMemTableRep(
+        allocator,
+        factory_.CreateMemTableRep(compare, allocator, transform, nullptr),
+        num_entries_flush_);
+  }
+  static const char* kClassName() { return "SpecialSkipListFactory"; }
+  virtual const char* Name() const override { return kClassName(); }
+  std::string GetId() const override {
+    std::string id = Name();
+    if (num_entries_flush_ > 0) {
+      id.append(":").append(std::to_string(num_entries_flush_));
+    }
+    return id;
+  }
+
+  bool IsInsertConcurrentlySupported() const override {
+    return factory_.IsInsertConcurrentlySupported();
+  }
+
+ private:
+  SkipListFactory factory_;
+  int num_entries_flush_;
+};
+}  // namespace
+
+MemTableRepFactory* NewSpecialSkipListFactory(int num_entries_per_flush) {
+  RegisterTestLibrary();
+  return new SpecialSkipListFactory(num_entries_per_flush);
+}
+
+#ifndef ROCKSDB_LITE
+// This method loads existing test classes into the ObjectRegistry
+int RegisterTestObjects(ObjectLibrary& library, const std::string& arg) {
+  size_t num_types;
+  library.AddFactory<const Comparator>(
+      test::SimpleSuffixReverseComparator::kClassName(),
+      [](const std::string& /*uri*/,
+         std::unique_ptr<const Comparator>* /*guard*/,
+         std::string* /* errmsg */) {
+        static test::SimpleSuffixReverseComparator ssrc;
+        return &ssrc;
+      });
+  SpecialSkipListFactory::Register(library, arg);
+  library.AddFactory<MergeOperator>(
+      "Changling",
+      [](const std::string& uri, std::unique_ptr<MergeOperator>* guard,
+         std::string* /* errmsg */) {
+        guard->reset(new test::ChanglingMergeOperator(uri));
+        return guard->get();
+      });
+  library.AddFactory<CompactionFilter>(
+      "Changling",
+      [](const std::string& uri, std::unique_ptr<CompactionFilter>* /*guard*/,
+         std::string* /* errmsg */) {
+        return new test::ChanglingCompactionFilter(uri);
+      });
+  library.AddFactory<CompactionFilterFactory>(
+      "Changling", [](const std::string& uri,
+                      std::unique_ptr<CompactionFilterFactory>* guard,
+                      std::string* /* errmsg */) {
+        guard->reset(new test::ChanglingCompactionFilterFactory(uri));
+        return guard->get();
+      });
+  library.AddFactory<SystemClock>(
+      MockSystemClock::kClassName(),
+      [](const std::string& /*uri*/, std::unique_ptr<SystemClock>* guard,
+         std::string* /* errmsg */) {
+        guard->reset(new MockSystemClock(SystemClock::Default()));
+        return guard->get();
+      });
+  return static_cast<int>(library.GetFactoryCount(&num_types));
+}
+
+#endif  // ROCKSDB_LITE
+
+void RegisterTestLibrary(const std::string& arg) {
+  static bool registered = false;
+  if (!registered) {
+    registered = true;
+#ifndef ROCKSDB_LITE
+    ObjectRegistry::Default()->AddLibrary("test", RegisterTestObjects, arg);
+#else
+    (void)arg;
+#endif  // ROCKSDB_LITE
+  }
+}
+}  // namespace test
+}  // namespace ROCKSDB_NAMESPACE